It looks like the biggest problems with fission reactors are still the people designing them.

The chairman, Gregory B. Jaczko, said that computations submitted by Westinghouse, the manufacturer of the new AP1000 reactor, about the building’s design appeared to be wrong and “had led to more questions.” He said the company had not used a range of possible temperatures for calculating potential seismic stresses on the shield building in the event of an earthquake, for example.

Mr. Jaczko said the commission was asking Westinghouse not only to fix its calculations but also to explain why it submitted flawed information in the first place. Earlier this year the commission staff said it needed additional calculations from Westinghouse to confirm the strength of the AP1000’s shield building. The building has not been built; the analysis of its strength and safety is all computer based.

roflwaffle wrote:It looks like the biggest problems with fission reactors are still the people designing them.

The chairman, Gregory B. Jaczko, said that computations submitted by Westinghouse, the manufacturer of the new AP1000 reactor, about the building’s design appeared to be wrong and “had led to more questions.” He said the company had not used a range of possible temperatures for calculating potential seismic stresses on the shield building in the event of an earthquake, for example.

Mr. Jaczko said the commission was asking Westinghouse not only to fix its calculations but also to explain why it submitted flawed information in the first place. Earlier this year the commission staff said it needed additional calculations from Westinghouse to confirm the strength of the AP1000’s shield building. The building has not been built; the analysis of its strength and safety is all computer based.

That seems a sort of unusual complaint. I mean, the shield building would be outside the reactor, there's not exactly going to be much of a difference in temperature on it in the first place, other than what you can get between summer and winter. I mean, does steel really have a huge difference in properties between say -10 and 30 degrees C? Although it does say that the shell could be used to passively dissipate heat, if the reactor was damaged. So, I guess they're concerned about what would happen if the reactor were to somehow catastrophically break down, and then coincidentally a major earthquake happened immediately after that? And that it's the designers fault that they didn't think to specifically simulate this specific unusual unlikely scenario ahead of time without being asked?

It seems to be fairly basic structural engineering, so I don't see why it would be left out. I don't know if it would significantly change the maximum acceleration at which the plant could safely shut down, but fission reactors aren't the kind of things we want to cut corners with.

roflwaffle wrote:It seems to be fairly basic structural engineering, so I don't see why it would be left out. I don't know if it would significantly change the maximum acceleration at which the plant could safely shut down, but fission reactors aren't the kind of things we want to cut corners with.

Well that's true enough, although it doesn't look like they're talking about the integrity of the wall with regards to repetitive strain or temperature differences there, it seems to be regarding running simulations of the structural integrity of the outer shell to withstand an earthquake of sufficient magnitude, apparently with regards to the shell being at different temperatures at the point in time when it happens.

And what's being talked about doesn't seem have anything to do with the speed of the plant shutting down, the purpose of building the shell in the way that it's described there, is that even if the core were to break apart or something like that, the design could passively dissipate that heat, so that without pumps or other active safety measures, it would be able to passively cool off on it's own, over time, even without any external intervention.

Soralin wrote:I mean, does steel really have a huge difference in properties between say -10 and 30 degrees C?

Potentially, yes. The shield building probably uses post-tensioned steel tendons, and a large change in temperature could substantially affect the tensile stress in the tendons and also the compressive stress in the concrete.

Think aftershocks. There is an earthquake, the primary circuit is broken, core is damaged, and the inside of the building is now very, very hot. What happens if there is a strong aftershock? After Fukushima, it only makes sense to revisit this topic with more care.

It's unclear whether thi is a serious complaint if jutst a request for more detailed work. In general, it'w a good thing if regulators ask for better work when they are not convinced. But the implication here is that asked cotton it before, and are still not convinced.

On the plausibility of fission reactors on an industrial scale, what are the thoughts on enrichment plants? Enrichment plants are necessary for mined uranium to be used in a nuclear power plant, right? While a nuclear power plant itself may take a long time to produce waste, the amount of waste and radiation released could be unpleasant, and the amount of energy used up in enrichment might offset(at least a little) the benefits of nuclear power. Factor in mining and transportation and renewables might have a fighting chance at being more efficient and cost effective than fission right now. Storage will always be a problem with fission reactors, no matter how insignificant the waste (even if it's as small an amount as is implied in this thread.)

Also, I think Fukushima shows that although an accident or disaster is unlikely and protected against, things can still go awry, with long lasting consequences. It doesn't have to be the dur da dur Soviet Union screwing around for things to go bad at a nuclear power plant.

I think some of the people who advocate wind and other renewable resources over nuclear power aren't doing so because of the number of people killed, but the potential number. The potential for destruction from a nuclear power plant is many times greater than that of a wind farm, solar ranch, or other similar methods. And one has control over whether or not one runs through a wind farm. One does not have control over the factors at the local nuclear power plant.

And can we tone down the "Everyone against nuclear power is completely ignorant,"? It's not very true.(some are some aren't, but there are many the same type of people on the pro nuclear side as well.)

Abgrund wrote:You won't get 1/3 energy conversion from D-T fusion. About 80% of the fusion energy, IIRC, is carried away by neutrons and is very difficult to recover. So if all global energy came from D-T fusion, and you multiply that 231 kg by as much as 5...

In a lithium-blanket tokamak, the neutrons pass through into the Li blanket, forming tritium, and dissipating their energy as heat in the lithium. That energy, from the neutrons, is tapped off from the lithium via a heat engine. The helium nuclei do not leave the plasma vessel, however, and they will stop within the plasma, contributing a bit to plasma heating.

...suffer from the computer disease that anybody who works with computers now knows about. It's a very serious disease and it interferes completely with the work. The trouble with computers is you play with them. They are so wonderful. - Richard Feynman

space_raptor wrote:The results of this poll so far make me very happy.

Nuclear energy is just beyond awesome, when it's done right.

That's a really big if. My main problem with nuclear energy is that most countries refuse to separate it from making nuclear weapons.

Correct me if I'm wrong here, I'm not a nuclear physicist, so I would like to be educated by individuals who know a lot more about this than I do. Isn't it true that a lot of countries that use nuclear energy to make power use certain isotopes because they can also be used to create weapons, when there are others that would be a lot safer?

Once again I apologize for my extremely limited amount of knowledge about the physics/chemistry behind all this.

Also, I voted in favor of nuclear energy. I think the potential is tremendous from what I've read. I'm always very angry when certain groups use events like Fukushima as an argument against nuclear energy.

space_raptor wrote:The results of this poll so far make me very happy.

Nuclear energy is just beyond awesome, when it's done right.

Isn't it true that a lot of countries that use nuclear energy to make power use certain isotopes because they can also be used to create weapons, when there are others that would be a lot safer?

Not really. It's possible, and sometimes countries do this when they are starting out. But the reactor designs you end up with are often compromises, not good at making weapons-grade plutonium nor at generating power. Plus you get security headaches, and military organizations as a rule don't mix very well with civilian operations either.

The Chernobyl design was an outlier here, it was in principle pretty good at both. But I am not sure the Soviets ever used them to make weapons plutonium. Soldiers and civilians didn't mix that well in the Soviet Union either. And nowadays that design is obviously not so popular anymore.

So people usually end up with specialized reactors to make weapons-grade plutonium, and other reactors to generate power.

space_raptor wrote:The results of this poll so far make me very happy.

Nuclear energy is just beyond awesome, when it's done right.

Isn't it true that a lot of countries that use nuclear energy to make power use certain isotopes because they can also be used to create weapons, when there are others that would be a lot safer?

Not really. It's possible, and sometimes countries do this when they are starting out. But the reactor designs you end up with are often compromises, not good at making weapons-grade plutonium nor at generating power. Plus you get security headaches, and military organizations as a rule don't mix very well with civilian operations either.

The Chernobyl design was an outlier here, it was in principle pretty good at both. But I am not sure the Soviets ever used them to make weapons plutonium. Soldiers and civilians didn't mix that well in the Soviet Union either. And nowadays that design is obviously not so popular anymore.

So people usually end up with specialized reactors to make weapons-grade plutonium, and other reactors to generate power.

See I wish the mainstream media was a little bit more knowledgeable about these kind of things. We're often so malinformed. I heard, of course on the news, that Japan used certain materials when it didn't have to necessarily for power, but they did anyway because it generated materials for nuclear weapons.

I understand this is a very complicated subject for the average person but it bothers me that nowadays with the 2 second news flashes there is no more time to properly explain things and put them in perspective.

Nescio wrote:See I wish the mainstream media was a little bit more knowledgeable about these kind of things. We're often so malinformed. I heard, of course on the news, that Japan used certain materials when it didn't have to necessarily for power, but they did anyway because it generated materials for nuclear weapons.

I understand this is a very complicated subject for the average person but it bothers me that nowadays with the 2 second news flashes there is no more time to properly explain things and put them in perspective.

Perspective: Yeah, that's a little...funky sounding to me. Japan constitutionally prohibited themselves from waging war or maintaining military (The Japanese Self-Defense Forces are, well, defensive in nature and technically is a part of their police) forces in Article 9 of their constitution following World War 2. They've arguably bent the rule a little but considering the continued cultural impact of the bombings of Hiroshima and Nagasaki, nuclear weapons are...probably still anathema to them.

Moreover, they've also ratified the Nuclear Non-Proliferation Treaty, which, as a non-nuclear state, would prohibit them from developing or manufacturing or assisting in the manufacture of nuclear weapons.

So...yeah, that news source is full of it.

Princess Marzipan wrote:Dear God, we seriously just went and dug up CITATIONS for TORTURE being a WAR CRIME.

Nescio wrote:See I wish the mainstream media was a little bit more knowledgeable about these kind of things. We're often so malinformed. I heard, of course on the news, that Japan used certain materials when it didn't have to necessarily for power, but they did anyway because it generated materials for nuclear weapons.

They were probably referencing MOX fuel which is a plutonium-uranium mixture typically produced to reprocess/dispose of nuclear weapons material.

Almost all modern nuclear reactors designs make use of design features and compromises that were originally used for nuclear reactors designed with military applications in mind (producing nuclear weapons materials). There are many reasons that these decisions were made. For example, the early military designs are well understood, so the engineers feel comfortable making assumptions about how they will behave under different conditions etc. It's easier to modify and improve these existing designs than to develop entirely new ones. And because the operating principles and requirements are roughly similar to existing reactors, the reactors can make use of pre-existing components and equipment.

However, this also means there are a lot of artifacts left over from the days of those early military reactors, such as fuel mixes (for generating/enriching weapons grade material) and containment systems (Military reactors require a certain amount of core access for removing weapons material) that make sense for a military reactor, but are unnecessary and potentially dangerous in a civilian reactor.

Newer reactors designs (gen 3+ and 4) are a lot better about not making these sorts of compromises, but almost all operating reactors are from earlier generations, due to the difficulty and expense of getting permission and funding to build new reactors, or even just to replace existing reactors.

Roosevelt wrote:

I wrote:Does Space Teddy Roosevelt wrestle Space Bears and fight the Space Spanish-American War with his band of Space-volunteers the Space Rough Riders?

What we learned in Fukushima is that when something like that happens, the probability is 100 percent.

That's not how probability works. Something can happen and still be rare. When an event that is rare happens, we don't have to suddenly re-consider all of our assumptions on the basis of that rare event actually being common or certain.

no one imagined that the external electricity supply from outside the plant that would cool the reactors could be disrupted.

This is plainly wrong. Otherwise, what was the point of the back-up generators? Yes they got flooded and didn't work when they were actually needed, but they were there. If no one had considered the possibility of external power disruptions, why have the back-up generators int he first place?

I'm consistently amused by how 'safe' people think nuclear reactors should be.The earthquake and tsunami were many times as destructive, and infinitely more deadly than the nuclear accident, but no, Fukushima Daichi should have been safer.

I imagine that if an asteroid were to strike San Diego and wipe out the entire Western seaboard, these same people would complain that SONG's containment structure should have deflected the impact and that it didn't is an indictment of the nuclear industry's corruption and it's dismissal of the possibility of asteroid impact as a short-sighted cost-saving measure.

Edit: apologies for the double post.

Roosevelt wrote:

I wrote:Does Space Teddy Roosevelt wrestle Space Bears and fight the Space Spanish-American War with his band of Space-volunteers the Space Rough Riders?

I sorry, I evidently saw that in a much different light than you. No matter the probability of any event happening before an event the probability of an event that has happened is one, it's just not a useful statement. However when you drive systems that can't fail or are so damaging when they do fail, than any assumption you make should take that into consideration. For instance the seawalls at another reactor were built much taller because someone felt that the possibility of them being overwhelmed had to be taken into account. The assumptions are generally drivers for the economy of a particular reactor. An economic choice rather than a safety choice.

EdgarJPublius wrote:I'm consistently amused by how 'safe' people think nuclear reactors should be.The earthquake and tsunami were many times as destructive, and infinitely more deadly than the nuclear accident, but no, Fukushima Daichi should have been safer.

The economic damage has the potential to be far greater than the direct costs of the earthquake and tsunami. An earthquake kills 10000 and you bury them and move on, however Fukushima and Chernobyl are gifts that keep on giving, both in an economic sense and a political sense. But my reason for posting wasn't to beat up on the reactor companies rather to suggest that the assumptions not be tailored to the economic needs of the builder. If we need to subsidize for safety, then we should do it.

Remember, that in addition to the loss of life and property damage, the Earthquake and Tsunami damaged other, conventional sources of energy, farmland and industrial facilities. The damage to Japan's fishing industry alone is expected to be greater than the cost of the nuclear cleanup.

Roosevelt wrote:

I wrote:Does Space Teddy Roosevelt wrestle Space Bears and fight the Space Spanish-American War with his band of Space-volunteers the Space Rough Riders?

EdgarJPublius wrote:I'm consistently amused by how 'safe' people think nuclear reactors should be.The earthquake and tsunami were many times as destructive, and infinitely more deadly than the nuclear accident, but no, Fukushima Daichi should have been safer.

I imagine that if an asteroid were to strike San Diego and wipe out the entire Western seaboard, these same people would complain that SONG's containment structure should have deflected the impact and that it didn't is an indictment of the nuclear industry's corruption and it's dismissal of the possibility of asteroid impact as a short-sighted cost-saving measure.

I can plug rather silly values into that and the argument still works. If I can spend 50¥ to make my reactor immune to tsunami, or asteroid strike, and I don't, then maybe it is an indictment of the nuclear industry's corruption.

The useful question here seems to be how much the life of a certain demographic is worth to you. How much does it cost to make the reactors safer and how many people, with what probability, might die if you don't? Divide the former by the latter and if the cost doesn't exceed whatever value you've put on a member of your society, do it.

Whenever you buy something, you establish a lower bounds on its value to you. Whenever you refuse to buy something, you establish an upper bounds on its value to you. Society invests a lot in its citizens and goes to considerable expense to keep them alive once its got them, the upper bounds value associated with such lives is not low.

If someone places their upper bound lower than yours... well, assuming your values would benefit from the purchase, you're not going to be best pleased with them.

I'm not interested in supplying any figures, although in support I will note that of as this point the Japanese have one operating reactor that they are getting ready to shut down. The area around the damaged reactors is still evacuated and there is skepticism that they will be able to clean it well enough for people to return, since it has never been done. So any numbers on the total costs would be guesswork.

The takeaway that I got from the article was that the use of probability was bad, not because the numbers were bad, but because the numbers encouraged carelessness. The reactors survived the tsunami intact. The generators got flooded. They were so sure of their numbers that they didn't make an effort to make sure that the generators would be available if the reactors survived.

The useful question here seems to be how much the life of a certain demographic is worth to you. How much does it cost to make the reactors safer and how many people, with what probability, might die if you don't? Divide the former by the latter and if the cost doesn't exceed whatever value you've put on a member of your society, do it.

If we make that exact calculation for everything, well... It leaves us all very bankrupt and very dead.

Surely the actual benefit should calculated in there as well?

Bdthemag: "I don't always GM, but when I do I prefer to put my player's in situations that include pain and torture. Stay creative my friends."

Griffin wrote:If we make that exact calculation for everything, well... It leaves us all very bankrupt and very dead.

Surely the actual benefit should calculated in there as well?

You don't know ahead of time what the actual benefit's going to be. Maybe you build your elaborate anti-asteroid system and nothing happens in the entire lifetime of the plant. You don't get to look at actual benefits, you only get to look at ones expressed as probabilities.

I'm suggesting that as the probability of an event goes down the more damaging to things/people you care about, or the less costly it has to be, to be worth guarding against. I don't see how that's going to make you bankrupt. The chances are your power station won't get hit by an asteroid. So, either you care too much about the lives concerned by the event, or you've found a real bargain for asteroid defence systems. Otherwise, you wouldn't have built the thing. You'd have done something else instead - like improving road safety; which, with its much higher probability of saving lives, would be worth doing even with a far lower value placed on life.

If it turns out you can buy an 80% probability of saving a life at the Road Safety Shop for £100, and you've spent £200 to buy a 40% probability at the Nuclear Safety Shop, you're just wrong about the value range of life. You've got your lower bounds and your higher bounds the wrong way around.

It does get worse. Do we value the death of a healthy 10 year old higher or lower than that of a sickly 90 year old?

The sickly 90 year old's death is prevented, and they are likely to die within the year regardless.

Lets go with "we value all prevented deaths equally".

Now, suppose we come up with a technology that "revives" people. It has a 99% success rate, but it only lasts for 1 heart beat. It then has a 99% chance of keeping them alive through the next heart beat.

70% of people who would have died prior to this device still die within 2 minutes. Nobody lives more than an hour past where they would have died before.

Does that count as a prevented death? A prevented death every second? While this is an extreme case, in practice we run into this: there are technologies that can be used to prolong someone's life by a relatively short window -- these windows get as short as you like (down to seconds), and as expensive as you can imagine. Few of them work in every situation -- but you can spend a nearly unbounded amount of money on the last few seconds, minutes, hours, days, and weeks of a person's life to attempt to push death back another few moments.

Calculating the cost-benefit of a life-saving measure, and its benefit, is more than just (average lives saved) divided by (cost) then sorting.

One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision - BR

The useful question here seems to be how much the life of a certain demographic is worth to you. How much does it cost to make the reactors safer and how many people, with what probability, might die if you don't? Divide the former by the latter and if the cost doesn't exceed whatever value you've put on a member of your society, do it.

Yes, that's how these things work. the cost of a disaster recovery is always guesswork. even after all the money is spent it can be intractable to track down all the expenses, all the authorized payments etc. And that's before you even get to the valuation of losses attributable to the disaster. The nuclear disaster isn't unique from the Tsunami in this.

These numbers represent more-or-less the best guesses on the cost of recovery from both disasters. If you have some better information than the people who came up with these guesses, or have found some more accurate guesses, then by all means, please share.

Otherwise, the actual evidence we have to judge this situation by points to the cost of the Earthquake/Tsunami being an order of magnitude larger than the cost of the nuclear accident

Roosevelt wrote:

I wrote:Does Space Teddy Roosevelt wrestle Space Bears and fight the Space Spanish-American War with his band of Space-volunteers the Space Rough Riders?

Yakk wrote:Are you familiar with the concept of "proof by contradiction"?

I see no contradiction in the idea that society might wish to save both the 90 year old and the 10 year old. That just shows that in one particular case the value of two lives could be held more or less equal, or at least fall close enough together that people would save both. It does not follow from that, that we would spend an unlimited amount of money to buy someone another minute of life.

Indeed, there are drugs that extend life for a few months, I believe in the case of cancer patients, that the NHS does not buy. Organs don't go to drug addicts, unless there's some special mitigating factor. I don't believe really old people tend to get organ transplants either.

All lives are not equal. We expect to buy some outcome for our investment. You can't just keep dividing the outcome based on the fact that the scale you're using to judge investment/returns for different cases isn't fine grained enough to clearly distinguish them in some cases when there are all these other cases where they can be distinguished. People don't seem to work that way.

That's yet to be seen. If there's an abnormal spike in cancers or something in that area, then it probably did.

Edit: We're not dealing with actual deaths here. We're dealing with might dies. What probability given what you know of similar situations.... At the end of the day what's rational to guard against will be based on your best guess.

I'm truly sorry I posted that link. I retract anything that I said about costs. It's not germane to the original post and is a waste of time since it is guesswork. The point was the hubris in a design that was good enough to withstand something greater than it was rated to take but which failed because the builders put so much faith in the low probability of the event, that when it happened it turned out they had placed the generators where they could be flooded. The direct analogy that comes to mind is storing your backups in the same building as your data center and then being surprised when you lose your data and your backups when the building goes up in flames. I had always taken the term redundant backup to mean that the backup should not be taken out by the same event that takes out the primary, barring comet strikes or whatever.

Yeah, but you're still dodging the question of, "How safe is safe?", which is really the point here. The existence proof of a failure just doesn't mean much. And with six serious accidents in history, and very few deaths, for an entire technology - that's pretty damned safe. So what probability of failure would be acceptable? If we had that probability to start with, and then you joined this conversation, would your position really be any different? It seems like you're arguing from a principle, not a number, and I'm not quite sure that you're, yourself, clear on what that principle is.

So much depends upon a red wheel barrow (>= XXII) but it is not going to be installed.

Copper Bezel wrote:Yeah, but you're still dodging the question of, "How safe is safe?", which is really the point here. The existence proof of a failure just doesn't mean much. And with six serious accidents in history, and very few deaths, for an entire technology - that's pretty damned safe. So what probability of failure would be acceptable? If we had that probability to start with, and then you joined this conversation, would your position really be any different? It seems like you're arguing from a principle, not a number, and I'm not quite sure that you're, yourself, clear on what that principle is.

I don't really care how safe is safe. What I care about is the why of failure. But if engineering has taught us anything is that you should at least ask the question what if. The designers of the Titanic were so sure it couldn't sink that it didn't have enough lifeboats for everyone on board. The generators at the site where most likely the cheapest things there. From my uneducated point of view all they needed to do was make sure that if the reactor survived that the generators did too. If the reactor is destroyed than the generators are worthless, but if the generators don't work when the reactor needs them then why have them at all. The point is the reactor survived, the gensets didn't. Hubris with a capital H.

That's yet to be seen. If there's an abnormal spike in cancers or something in that area, then it probably did.

Edit: We're not dealing with actual deaths here. We're dealing with might dies. What probability given what you know of similar situations.... At the end of the day what's rational to guard against will be based on your best guess.

Japan Times wrote:"If the current radiation dose estimates are correct, (cancer-related deaths) likely won't increase," said Michiaki Kai, professor of radiation protection at Oita University of Nursing and Health Sciences."If there is any health impact from radiation, it would be too small to detect, and in any case it would be masked by other, much larger factors, such as smoking and diet," Kai said.

Roosevelt wrote:

I wrote:Does Space Teddy Roosevelt wrestle Space Bears and fight the Space Spanish-American War with his band of Space-volunteers the Space Rough Riders?

morriswalters wrote:The designers of the Titanic were so sure it couldn't sink that it didn't have enough lifeboats for everyone on board.

And thanks to that disaster, all the subsequent ships were made with more lifeboats than people onboard. This is what should happen with nuclear facilities, but due to extreme anti-nuclear popular position, new, safer fission plants can't be built. Fukushima construction started at late sixties. Many countries don't build new nuclear plants and, as disabling the existent ones is dangerous and expensive, we have each time more obsolete, old reactors.

I definately agree; thorium is the way to go; based on current data, it is a hell of a lot less damaging in the unlikely event that it goes wrong-and the significance of the problem should definately be factored in with its probability when you're deciding whether to do anything about it-that's just game theory: no-one wants to be in the middle of another Chernobyl. I mean, unless they're a nihilist, suicidal or just plain stupid (not implying that the former two are the same as the latter, as I have been both).

Insoluble? No. But neither are the problems presented by nuclear power, and the problems presented by nuclear are cheaper and easier to solve, too. Well, they are if you can get people to rationally address the issues, because the majority of issues are a matter of politics and public perception rather than true engineering hurdles.

Princess Marzipan wrote:Dear God, we seriously just went and dug up CITATIONS for TORTURE being a WAR CRIME.

Japan Times wrote:"If the current radiation dose estimates are correct, (cancer-related deaths) likely won't increase," said Michiaki Kai, professor of radiation protection at Oita University of Nursing and Health Sciences."If there is any health impact from radiation, it would be too small to detect, and in any case it would be masked by other, much larger factors, such as smoking and diet," Kai said.

Apart from the obvious inconvenience of evacuating the area then, it doesn't sound like they screwed up that bad. Unless it'd be cheaper than the clean up to do things differently, why bother?

@NemAs we speak the radiation continues to leak into the environment and workers at the plant are exposed at a much higher rate than the surrounding populace. But mainly it destroys public confidence in the concept of nuclear power.